1/6. Blaschkolinear malformation syndrome in complex trisomy-7 mosaicism.Results of repeated peripheral blood chromosome studies were normal in a boy with intrauterine growth retardation, short stature, moderate mental retardation, and multiple minor anomalies. At age 9 years it was recognized that the swirls of pigmentation/depigmentation on his trunk, linear streaks on his limbs, and body asymmetry were suggestive of chromosomal mosaicism. Four skin biopsies were obtained under anesthesia during a dental procedure. All showed mosaicism for a normal cell line, a line with an extra chromosome 7, and a cell line with an extra small ring. In one biopsy, there was a fourth cell line with an extra chromosome 7 and the ring. fluorescence in situ hybridization (FISH) with a chromosome 7 paint confirmed trisomy 7 and the chromosome 7 derivation of the ring. This young man's intra-uterine and postnatal growth retardation is an aneuploidy effect, whereas his asymmetry reflects a mosaicism effect that should have aroused suspicion of tissue-limited mosaicism before the development of obvious Blaschkolinear skin pigmentary dysplasia.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/6. Clinical, cytogenetic, and fluorescence in situ hybridization findings in two cases of "complete ring" syndrome.The term "ring syndrome" was proposed to describe a phenotype of growth failure without major malformations due to a ring autosome. The growth failure is thought to be caused by instability of the ring chromosome leading to aneusomy and cell death. Most previous studies of ring chromosomes were based on standard cytogenetic banding techniques and were limited to microscopically detectable deletions in the ring chromosomes. We report on two patients with complete ring (4) and ring (9) chromosomes, respectively. The first was a 15-month-old girl and the second was a 16-month-old boy. They both presented with severe, symmetrical growth failure and normal psychomotor development in the absence of malformations. Their parents had a normal phenotype. The first case had a whorled pattern of hyperpigmentation and hypopigmentation on part of the face and chest, and the second case had a patchy hyperpigmented rash on the trunk. Peripheral blood karyotype of the first patient was 46,XX, r(4)(p16.3q35.2) and of the second 45,XY,-9/46,XY,r(9)(p24q34.3). G-band analysis suggested no loss of material in the ring chromosomes. These findings were confirmed by fluorescence in situ hybridization (FISH) analysis using chromosome-specific subtelomeric probes. The common human telomeric sequences were intact in the first patient but absent in the second patient. The cytogenetic and FISH data in our two cases provide further evidence for the existence of a "complete ring" phenotype independent of the autosome involved. Pigmentary skin changes are a useful clinical sign of mosaicism caused by the ring instability.- - - - - - - - - - ranking = 5keywords = hybridization (Clic here for more details about this article) |
3/6. Recurrent digital fibroma, focal dermal hypoplasia, and limb malformations.Recurrent digital fibroma of infancy generally is considered a sporadic tumor of childhood. We describe the case of a mother with recurrent digital fibroma at a young age who gave birth to a daughter with focal dermal hypoplasia, coloboma of the iris and eyelids, anal atresia, and extensive limb malformations. When the infant was 3 months old, fibromas started to appear at the fingertips. The cases of three additional patients are described, with a similar combination of multiple digital fibromas, pigmented marks on the temporal region, and limb malformations. One of these patients has consanguineous parents. The clinical findings overlap partially with Gorlin-Goltz syndrome, which has been renamed by some authors "microphthalmia with linear skin defects" (MLS). Since the skin signs are clearly different, however-more like those of Setleis syndrome ("forceps mark" temporal dysplasia)-the patients described here seem to have a new combination of congenital malformations. Deletion of distal Xp, known to occur in some MLS patients, was not detected using cosmids in fluorescence in situ hybridization. This pattern of digital fibroma with congenital malformations seems to represent a new syndrome.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
4/6. Analphoid 3qter markers.Two cases of marker chromosomes derived from a non-centromeric location were studied to determine the characteristics of these markers with respect to the presence of functional centromeres and whether an associated phenotype could be described. The markers were characterized by fluorescence in situ hybridization and centromeric protein studies. Assessments were done to identify clinical features. Case 1 is a girl referred at age 1.5 years with swirly areas of hyperpigmentation, bilateral preauricular pits, hypotonia, developmental delay, and seizures. Case 2 is a male first evaluated as a newborn and then later during the first year of life. He had streaky hypopigmentation, right preauricular pit, accessory nipples, postaxial polydactyly, asymmetric cerebral ventricles, duplicated right kidney, a right pulmonary artery stenosis, and seizures. mosaicism for an extra marker from the 3qter region was present in both cases. Both markers had a constriction near one end and were C-band negative. Centromeric protein studies indicated absence of CENP-B, presence of CENP-C (data for case 1 only), and presence of CENP-E. Marker chromosomes were thus identified with a chromosomal origin far from their usual centromeric region and yet appeared to have functional centromeres. These two cases did not permit a specific clinical phenotype to be ascribed to the presence of tetrasomy for 3q26.2 approximately 3q27.2-->3qter.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
5/6. prenatal diagnosis of tetrasomy 47,XY, i(12p) confirmed by in situ hybridization.A case of tetrasomy i(12p) detected prenatally is reported. The patient, a black, 32-year-old G3P2002 at 24 weeks' gestation with an unremarkable family history presented herself for prenatal care. Ultrasound examination showed a fetus with diminished femoral and humeral lengths, and hydramnios. A level II scan confirmed the presence of an omphalocele. amniocentesis at 31 weeks showed 47,XY, i(12p) karyotype. An infant with multiple congenital anomalies was delivered at 34 weeks. The infant died after 5 h. Genetic and ultrasonographic examinations in the third trimester were helpful in the investigation of this fetus with multiple congenital anomalies. The careful, complete team counselling afforded by this approach enabled the mother and family to be well adjusted to the strong possibility (and subsequent reality) of an abnormal infant.- - - - - - - - - - ranking = 4keywords = hybridization (Clic here for more details about this article) |
6/6. Mosaic loss of 15q11q13 in a patient with hypomelanosis of Ito: is there a role for the P gene?We report a patient with mental retardation, behavioral disturbances, and pigmentary anomalies, consistent with the phenotype of hypomelanosis of Ito (HMI), and in whom cytogenetic analysis revealed mosaicism for an unbalanced translocation. His karyotype is 45, XY,-7,-15, der(7)(7:15)t(q34:q13)/46,XY. He is therefore monosomic for 7q34 to qter and 15pter to q13 in the cells containing the translocation. The human homolog (P) of the p gene (the product of the mouse pink-eyed dilution locus) maps to 15q11q13. Loss of this locus is believed to be associated with abnormalities of pigmentation, such as the hypopigmentation seen in patients with deletions of 15q11q13, and the Prader-Willi and Angelman syndromes. Mutations within the P gene have also been associated with tyrosinase-positive (type II) oculocutaneous albinism. Using fluorescence in situ hybridization, we confirmed that our patient is deleted for one copy of a P gene probe in the cells with the unbalanced translocation, and for loci within the region critical for the Prader-Willi/Angelman syndromes. Although hypomelanosis of Ito is a heterogeneous disorder, we postulate that, in our case and potentially in others, this phenotype may result directly from the loss of specific pigmentation genes.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |